The present invention generally relates to a closure member for a container and, more particularly, to a pierceable closure member for a medical bottle such as a vial.
In any country where the medical administration is more or less advanced, standards for medical supplies are naturally strict with no exception to the quality of a closure member for a medical bottle which contains therein a medicament, either solid or liquid, including, for example, an injection solution and a medical powder to be subsequently dissolved by injecting a liquid into the bottle. In other words, the closure member for use on the medical bottle should have, and is required to have, a relatively high quality so that the medicament contained in the bottle will not be contaminated by the dissolution of, in reaction with or in contact with material and/or additives used during the manufacture of the closure member. Once the medicament has been contaminated in any way, some or all of the pharmaceutical characteristics, for example, potency, color, clarity, activity and pH value, of the medicament will be adversely affected.
To avoid the above discussed problem, various proposals have hitherto been made to improve the closure member of the type referred to above. Of them, a closure member coated in part or in whole with a film of chemically stable material, such as fluorocarbon resin or Teflon (Du Pont's Reg. Trademark) has largely been accepted because of its chemical performance superior to that afforded to any other coating materials. This is exemplified by the U.S. Pat. No. 3,198,368, patented Aug. 3, 1965, U.S. Pat. No. 3,552,591, patented Jan. 5, 1971, U.S. Pat. No. 3,760,969 patented Sept. 25, 1973. In particular, the second mentioned U.S. patent discloses, in addition to the use of the Teflon film, the provision of an annular groove formed on the surface area of the closure member, which faces the bead of the bottle mouth, for accommodating a liquid which leaks from the interior of the bottle and radially outwardly through the area of contact of the periphery of the Teflon film to the bead of the bottle mouth.
Although such a closure member available for use on a medical bottle, particularly a vial, may be generally satisfactory, it still has a problem when used under circumstances of reduced pressure, i.e., on a substantially vacuum-filled vial. A substantially vacuum-filled container is not a recent development and canned food industries have long manufactured, and are currently manufacturing, canned food products contained in substantially vacuum-filled cans. However, with a diversity of medicaments hitherto developed, pharmaceutical industries have recently marketed vacuum-filled vial products. Those suited for storage in vacuum-filled vials include, for example, some of the medicaments which tend to be pharmacologically inactivated when placed under the atmosphere and some powdery medicaments which are used to prepare an injection solution by injecting a liquid, such as distilled water, into the vial. Some of the medicaments which have hitherto been stored in vials with an inert gas filled therein may also be stored in vacuum-filled vials.
In any event, when the conventional closure member, such as disclosed in any one of the previously mentioned patents, is used on a vial which is either vacuum filled or filled with an inert gas and, therefore, requires a relatively high fluid-tightness to be established in such vial product, it has been found that fluid leakage takes place particularly during the manufacture of the vial product. This will now be discussed in detail.
In general, the vial product is manufactured by filling a required amount of medicament in a vial, then capping a closure member on the mouth of the vial, and finally cupping a metal sealing ring to clamp the closure member and the mouth of the vial together thereby to secure the closure member firmly and tightly to the vial. When it comes to products to be stored in a vacuum-filled vial or in a vial filled with an inert gas, the withdrawal of air from the vial or the injection of the inert gas into the vial is carried out after the filling of the medicament into the vial and before the capping of the closure member on the vial mouth. For a substantial period of time after the capping step before the subsequent cupping step, the vial with the closure member thereon is generally allowed to stand under the atmosphere in the form with the closure member having been not yet clamped tightly to the vial mouth by means of the metal sealing ring. It is during this period of time that the fluid leakage, i.e., escape of inert gas from the vial or intrusion of external air into the vial, is more likely to occur than at any other opportunities during the manufacture of the vial product. This is true even where the closure member has an annular leg integrally formed with the closure member and covered with the Teflon film for engagement into the vial mouth, such as disclosed in the last mentioned U.S. patent.
In view of the foregoing, it has been desired to provide a pierceable closure member which satisfies not only all of the existing requirements for the closure member on the medical vial to meet, such as resealability with no coring, inertness to chemicals, resistance to aging, inexpensiveness and others, but also a requirement concerning the capability of holding a fluid tightness particularly when the vial is evacuated to a predetermined degree of vacuum.